1. Field of the Invention
The present invention relates to a signature delivery section of a folding machine of a rotary press. More particularly, the invention relates to a paper guide unit in a signature delivery section of a folding machine of a rotary press. The folding machine allows the size of signatures to be varied arbitrarily. The paper guide unit comes into contact with and guides rear end portions of signatures projecting from the circumference of a delivery fan while the signatures are received in the delivery fan and then drop onto a conveyor located under the delivery fan.
2. Description of the Related Art
In a rotary press, web printed in a printing section is folded and cut at a folding machine to become signatures. The signatures are sent to a delivery fan in a signature delivery section.
Each signature drops in a vertical posture into a space defined by adjacent vanes of the delivery fan. Each signature is received in its space with its rear end portion projecting from the circumference of the delivery fan. As the delivery fan rotates, each signature is rotationally moved and changes its posture from vertical to horizontal. As the delivery fan rotates further, each signature is further moved rotationally and drops onto a conveyor located under the delivery fan.
The conveyor is vertically movable in accordance with signature thickness, so that the gap between the circumference of the delivery fan and the upper surface of the conveyor can be adjusted in accordance with signature thickness.
Through the above-mentioned gap adjustment, signatures are conveyed on the conveyor without jamming.
In order to prevent flutter or droop of signature rear end portions projecting from the circumference of the delivery fan, there is generally provided a paper guide unit which comes into contact with signature rear end portions in order to guide them toward the conveyor.
A conventional technique related to the above-mentioned paper guide unit is disclosed in, for example, Japanese Utility Model Publication No. 53-37682 and Japanese Patent Publication No. 1-17980.
The paper guide unit disclosed in Japanese Utility Model Publication No. 53-37682 has a paper guide whose shape corresponds to the trajectory of vane tips of a rotating delivery fan.
The paper guide has a mechanism for coping with a signature jam. Specifically, upon a signature jamming between the delivery fan and the paper guide for some reason, the jamming pressure causes the paper guide to move parallel away from the delivery fan against a spring force.
The paper guide unit disclosed in Japanese Patent Publication No. 1-17980 includes movable means and adjusting means. The movable means enables a paper guide to move away from a delivery fan along rails provided on both sides of the paper guide. The adjusting means enables an operator to move the movable means through operation of a handle so as to adjust the gap between the delivery fan and the paper guide.
The paper guide unit disclosed in Japanese Utility Model Publication No. 53-37682 does not have adjusting means for adjusting the gap between the delivery fan and the paper guide through movement of the paper guide away from the delivery fan. Thus, even when the size of signatures is changed, the gap between the delivery fan and the paper guide cannot be adjusted accordingly. Consequently, signature rear end portions projecting from the circumference of the delivery fan cannot come into proper contact the paper guide. Specifically, the following problems are involved.
(1) When the gap between the delivery fan and the paper guide is excessively wide for the size of signatures, rear end portions of signatures may not come into contact with the paper guide or may come into only slight contact. As a result, the signature rear end portion may flutter, droop, or exhibit like behavior while the signature is rotationally moved with rotation of the delivery fan.
Subsequently, the signature drops onto a conveyor such that its rear end portion is knocked down on the conveyor surface. The impact causes the signature rear end portion to jump up on the conveyor surface. As a result, leaves of the signature may be turned over at a corner section or across the entire width of the signature rear end portion. A subsequent signature drops onto and presses the turned-over leaves, causing formation of a fold at the signature rear end portion.
(2) When the gap between the delivery fan and the paper guide is excessively narrow for the size of signatures, a contact area between rear end portions of signatures and the paper guide becomes relatively large, resulting in an increase in frictional resistance therebetween. This disturbs the timing of the signature rear end portion dropping onto a conveyor. For example, the dropping may be delayed.
As a result, signatures fail to drop onto the conveyor in an orderly manner and be conveyed at regular overlapping intervals.
If a signature drops onto the conveyor in a misaligned manner, the signature may be caught by a side plate or the like provided on either side of the conveyor and serving as a paper guide, thus remaining in place on the conveyor. As a result, following signatures will accumulate on the stopped signature, causing signature jamming.
The paper guide unit disclosed in Japanese Patent Publication No. 1-17980 has the adjusting means for enabling an operator to horizontally move the paper guide toward or away from the delivery fan so as to adjust the gap between the paper guide and the delivery fan in accordance with the size of signatures.
However, the paper guide is in a flat shape, which does not correspond to the trajectory of vane tips of a rotating delivery fan.
Further, the paper guide faces the delivery fan in a substantially vertical posture. Accordingly, the gap between the delivery fan and the paper guide is not constant over the entire paper guide. In other words, the gap becomes relatively wide at a certain point on the paper guide and becomes relatively narrow at another point. Even though the gap is adjusted according to the size of signatures through movement of the paper guide effected with the adjusting means, there are involved problems similar to those in the case of the above-mentioned paper guide unit disclosed in Japanese Utility Model Publication No. 53-37682.
Also, even when signature jamming occurs on the conveyor and propagates up to the gap between the delivery fan and the paper guide due to accumulation of following signatures, the paper guide is not adapted to respond to an increased jam pressure and move away from the delivery fan, resulting in a mechanical breakage.
Further, since the paper guide cannot be moved far away from the delivery fan during work for coping with a signature jam, a worker takes a long time and must perform burdensome operation to remove jammed signatures, so that a significant burden is imposed the worker.